# i = 0
#
# while i < 5:
#     print(i)
#     i += 1

# 0 - 100 累计求和
# i = 0
# a = 0
# while i <= 100:
#     a += i
#     i += 1
#
# print(a)

# 0 - 100 偶数求和
i = 0
a = 0
while i <= 100:
    if i % 2 == 0:
        a += i
    i += 1
print(a)